Method of making an array of helical inductive coils



Aug. 4, 1964 H. E. AUSTEN 3,142,889

METHOD OF MAKING AN ARRAY 0F HELICAL INDUCTIVE COILS Original Filed June 12, 1958 2 Sheets-Sheet 1 FIG. 3

' 6 FIG. 2 5 8 so i INVENTOR HERMAN E. AUSTEN Maw HIS AT TOR NEYS 1964 H. E. AUSTEN 3,142,889

METHOD OF MAKING AN ARRAY OF HELICAL INDUCTIVE COILS Original Filed June 12, 1958 2 Sheets-Sheet 2 INVENTOR HERMAN E. AUSTEN HIS ATTORNEYS United States Patent 3,142,889 METHOD OF MAKING AN ARRAY OF HELICAL INDUCTIVE COILS Herman E. Austen, Trotwood, Ohio, assignor to The National Cash Register Company, Dayton, Ohio, a corporation of Maryland Original application June 12, 1958, Ser. No. 741,583, now Patent No. 3,051,930, dated Aug. 28, 1962. Divided and this application Aug. 31, 1959, Ser. No. 836,984

7 Claims. (Cl. 29-1555) This invention relates to a process and means for making an array of helical electrical coils, and, more specifically, to the process and means for making such an array which is invested in solid dielectric material except for axial holes in the coils.

This application is a division of United States patent application Serial No. 741,583, filed June 12, 1958, now Patent No. 3,051,930, issued August 28, 1962.

In electronic computer and similar applications, the use of bi-stable magnetic data storage devices is becoming increasingly widespread. In this regard, there has recently been developed a bi-stable magnetic data storage device of the type which takes the form of a conductor or wire which is passed through axial holes of alined helical electrical coils. Magnetic devices of this type are also electrically conductive and may be made entirely of a magnetic material having substantially square hysteresis characteristics or the core of the magnetic storage device may be made of an electrically conductive but non-magnetic material, such as copper wire, having an electro-plated sheath of magnetic material having substantially square hysteresis loop characteristics.

In either instance, with the magnetic device passed through alined helical electrical cores, the coincident application of current to a row of coils and to a selected one of the magnetic devices associated with that row, produces the required ampere-turns which results in the magnetic saturation of that selected section of the magnetic device.

As magnetic data storage devices of this type are becoming increasingly popular, the desirability of a method of manufacture of an array of helical electrical coils which are arranged to accommodate magnetic storage devices of this type, is apparent.

It is, therefore, an object of this invention to provide an improved process for the manufacture of an array of helical electrical coils.

It is another object of this invention to provide an improved process for the manufacture of an array of helical electrical coils which are invested in a solid dielectric material except for axial holes through the coils, constituting a panel.

It is a further object of this invention to provide an improved process for the manufacture of an array of helical electrical coils which are invested in a solid dielectric material, constituting a panel, and further pro vides that such panels may be stacked together with other identical panels so the corresponding coils of the arrays of each panel have their axial holes in alinement.

' For a better understanding of the present invention, together with further objects, advantages and features thereof, reference is made to the following description and accompanying drawings, in which:

FIG. 1 is a perspective of a plate which holds pins on which the coils are wound, said plate also being one of two which together form a mold for casting an investment material around the coils,

FIG. 2 shows the left hand portion of a section on the line 2-2 of FIG. 1, with five winding pins shown in full and showing two coils and part of a third wound,

FIG. 3 is a detail, partly in vertical section, of the first pin of a row, having a coil started thereon by means of a coil winding device,

FIG. 4 shows the substance of FIG. 3 with the coil winding device rotated clockwise 90 deg., as viewed from the top,

FIG. 5 is an exploded perspective view of the two plates forming the investment mold, showing the pins for the array of coils, including one row, the spacer between the plates, and the bolts for fastening together,

FIG. 6 shows the assembled mold ready for casting the investment material therein,

FIG. 7 is a broken sectional view taken on the line 77 of FIG. 6, only the first three pins and coils being shown,

FIG. 8 is a plan view of a finished panel showing the electric leads, common to the coils of a row, and

FIG. 9 is a cross section through a stack of panels, partly broken away, showing the top four coils and four panels and their associated magnetic storage devices.

For convenience, the coils of each panel are, in this disclosure, arranged in a square pattern of alined rows and columns, the coils of a row being formed of a continuous electric conductor, by novel means. It is to be specifically understood, however, that this arrangement has been indicated only for the purpose of clearly describing the process of this invention in that a myriad of alternate arrangements of the coils in the array may be produced through the practice of this novel process.

General Description of the Molding Means The invention is adapted for making very compact and small coil arrays in single or multiple panel arrangements, and dimensions of parts of a successful example of the invention will be given, but such dimensions are not in any way to be considered as limiting the scope of the invention.

FIG. 1 shows a plate 20, made of metal or other rigid material, about 2% inches square and of a thickness of /8 of an inch having bored therethrough a square array of pin-receiving holes 21, numbering ten in a row and ten in a column. These holes 21 are spaced 0.1 inch apart in columns and rows, and are 0.015 of an inch in diameter. The pins 22, a full array of which is shown in FIG. 5, are /3 of an inch long, thus projecting of an inch above the plate 20. A top plate 23 (FIGS. 5, 6 and 7) of the same dimensions, and an array of holes 24 to match holes 21 are provided to form, with spacer 25, a complete mold as shown in FIG. 6, with an opening 26 into which the investing material is poured. Locating pins 27 and 28 in the bottom plate cooperate with holes 29 and 30 in the top plate to aid in assembling the top and bottom plates 20 and 23 and the spacer 25. Bolts 31, 32, 33 and 34 fasten the assemblage of plates and spacer together. The spacer is about of an inch, making a space of the same dimension between plates 20 and 23 forthe height of the coils on the pins.

Studs 35, 36, 37 and 38 are provided on the plate 20 to make bolt-receiving holes in the molded panels whereby a number may be fastened in a stack. Studs 39 and 40 are provided in plate 20 to make alining holes for receiving alining rods before the stack of panels is fastened together by bolts.

The Coil Winding Means The coils forming one row of a panel are made of a continuous electrically conductive wire, of 0.005 of an inch in diameter with an electrical insulating coating of about 0.0005 of an inch, making the total diameter of the wire 0.006 of an inch. Ten turns of the wire in a closely wound helical coil is 0.060 of an inch in height which is the clearance between plates 20 and 23 of the molding means.

Referring to FIG. 2, a free end 50 of a wire supply is laid over the edge of plate 20 to form a terminal and from there extends to the first pin 51 of a row, and is wound around pin 51, upwardly, for ten turns and passed onto thenext pin 52, by span 53, where it is wound up- Wardly for tenturns and passed by span 54 to pin 55 which is shown partly wound for the purpose of explaining' the method of winding. As shown, the supply end of the wire passes upwardly through a hollow feed tube '56. The supply end 57 of the wire extends to and is delivered from a supply spool, not shown.

" The axis of feed tube 56' is parallel to pin 55, and to the .other pins with which it cooperates, but is spaced sideways by the forming cylinder 58 attached thereto. The forming cylinder 58 fits over pin 55, or any other pin on which a coil is being wound. Forming cylinder 58 is beveled at the bottom as shown at 59 (see also FIG. 3) and charnfered on the trailing edge 60, to form a coiling foot, as shown in FIG. 4, the cylinder 58 and tube 56 forminga coiling tool. The coiling tool comprising tubes 56' and 58 forms a unit rotatable around the pin over which tube 58' fits. The rotation of the coiling tool unit is, in a clockwise direction, as viewed from the top, because the chamfer 60 forms the trailing edge which presses down on the last turn of the coil being formed. If chamfer 60 was on the other side of the bevel, the coiling tool unit would be rotated counter-clockwise around the pin being wound. The bottom offorming tube 58 fits snugly against the pin around which the coil is being wound, and the bottom of tube 58 rides on top of'the last-wound turn. In consequence, the forming tool rides up as the coil is wound so the wire supply is always fed from tube 56 at the proper level and the chamfered portion 60 forces the new turn against the last.

The opening at the bottom end of feed tube 56 is rounded as shown at 61 in FIG. 3 to form an easy passage for the supply end 57 of the wire.

A slight downward pressure of the coiling tool, as it is being rotated by using the upper end of feed tube 56 as. a crank, is desirable to form a tight coil.

After ten turns have been made on a pin, the coiling tool is removed, allowing the wire supply 5'7 to feed through tube 56 so the coil, just made, is not disturbed. The forming tube is then placed over the next pin, the necessary slack in wire 57 being provided and then taken up as the tool is in place on the next pin, leaving but the span 53, 54, etc., between coils.

The coiling is repeated on the pins of a row in sequence, until the last pin is reached. The tool 56, 58 is removed and sufficient wire isfed out of tube 56 to lay a free end 62' (see FIG. 7) over plate 20, which will extend :beyond the mold and therefore be available as an electric terminal just as free end 50'which was described with reference to FIG. 2. The free end 62 is cut to the desired length, which completes the windings of coils in one row.

The other nine rows of pins arev similarly wound with coils, the rows each having terminal leads like leads 50 and 62', shown in the various figures of the drawings.

After all the coils of all the rows are wound, the spacer 25 (FIG. 5), which is of U-shape, is set onto plate 20, the opening of U accommodating the pins and coils. The spacer 25 is provided with clearance and positioning holes which cooperate with pins 27 and 28 and bolts 31, 32, 33 and 34. The top plate 23 is set in place by the aid of pins 27 and 28, the portion of the pins 22 which project above the coils entering holes 24. The bolts 31, 32, 33 and 34 are secured in place, forming the mold as it appears in FIG. 6.

, The mold of FIG. 6 is set on edge with the opening 26 up and an investment material is poured in to fill the space enclosed by the spacer, thus surrounding the coils. This investment material may be heat-liquifiable wax which hardens on cooling, a liquid monomer material which may be polymerized to a solid, or equivalent material which may be cast, as long as it is a dielectric.

be secured together, as shown in FIG. 9. The locating holes '72 and '73, in the investment material of the panels of a stack, are placed in alinement and rods, such as rod 74, are passed through to aline corresponding coils of the panels so the axial holes of corresponding coils of the panels of a stack are in alinement. The panels of a stack may be bolted together through holes '75, 76, 77

and 78 (FIG. 8) provided therefor and formed in the molding process by studs 35, 36, 37 and 38 (FIG. 1).

It will be apparent that the winding of a coil need not commence on the base plate but at a point thereabove as determined by a shoulder on the'winding pin, as shown at 96 in FIG. 2, in which case the coil will be shorter and not reach the surface of the panel formed by the base plate. The foregoing method of'making a shorter coil which does not reach one of the surfaces of a panel may be advantageous in physically isolating coils which are end to end in a stack of panels, even though the wire of which the coils are made is electrically insulated. The alined axial holes of corresponding coils of a stack of panels are served by a bistable magnetic data storage device 80 (FIG. 9) in the form of a wire, or equivalent, passed through the alined coils. The magnetic device 80 preferably is made entirely of magnetic material having a substantially square hysteresis loop so that it may be magnetized to assume one polarity or another and keep such state until a magnetizing force of opposite sense and of sufiicient value is applied. In another form of magnetic device only a. sheath thereof is of magnetic material, the core thereof preferably being of electrically conductive but nonmagnetic material, such as a copperwire having an electroplated magnetic sheath. the device should be electrically conductive. Current applied to a row of coils and to a selected one of the magnetic devices associated with the row, both currents together constituting the necessary strength to produce magnetic saturation of that selected section of the device associated with said row of coils, and both currents being in a direction aiding such saturation, will cause data to be stored magnetically in the so-selected section of the said device. The data so stored in any section of any device associated with a row of coils may be read and erased by passing a current through the row of coils in the direction and of a strength to produce saturation of the associated areas of the devices associated with the row of coils, in the opposite magnetic polarity, the presence of data being indicated in a magnetic device by an electric impulse being produced therein as the magnetic polarity of a section having data stored therein is reversed in magnetic polarity. The reading of the data automatically erases it because of the change in magnetic polarity of the affected section of a magnetic device.

Resort may be had'to twisting such device on its longitudinal axis to make the easy path of magnetization nearly parallel to the circumference thereof in a helical manner.

Such expediency is indicated in the publications The Twistor Memory Device, published in Bell Laboratories Record of December 1957, pages 488 and 489, and in A New Storage Element Suitable for Large-Sized Memory Arraysthe Twistor, published in the Bell System Technical Journal of November 1957, volume XXXVI, number 6, pages 1319 to 1340, inclusive.

The invention is not to be deemed limited to the dimensions of the coil arrays, their configurations, or their component parts, as the invention pertains to processing steps and combinations of parts regardless of dimensions or as to particular materials, as equivalents maybe used.

In either instance, 7

What is claimed is:

l. The method of making an array of helical inductive coils embedded in a hardenable plastic dielectric material for use in a memory device, the axial holes of said coils being free of the dielectric material including the steps of providing a top and a bottom die plate having axially alined holes to receive pins on which the coils are wound, said holes defining the configuration of the coil array, and a U-shaped separator piece having the thickness of the desired coil length and having wire-clearance slots; setting pins in the holes in the bottom plate; winding coils on said pins, with insulated electrically conductive wire, in an electric series, leaving uncoiled wire ends extending beyond the edge of the bottom plate; placing the U-shaped separator around the entire group of pins and over the extended wire, the wire being accommodated by the clearance slot; placing the top plate on the pins and separator to form a mold having an opening at the mouth of the U of the separator; casting a hardenable plastic dielectric material through the mouth of the mold to surround and embed the coils; hardening the plastic dielectric material; and removing the array of embedded coils from the mold.

2. The method of claim 1 in which the plastic dielectric material is poured into the mold as a liquid and is hardened to a solid.

3. The method of claim 2 in which the plastic dielectric material is thermoplastic.

4. The method of claim 2 in which the plastic dielectric material is thermosetting.

5. The method of making an array of rows and columns of helical inductive coils embedded in a hardenable plastic dielectric material for use in a memory device, the axial holes of said coils being free of the dielectric material, including the steps of providing a U-shaped separator piece having the thickness of the desired coil length and having wire-clearance slots, a top and bottom die plate each having a pattern of holes therein which is congruent with the pattern of holes in the other plate to receive pins on which the coils are wound, said holes being arranged in rows and columns according to the configuration of the array and the pins fitting in said holes being in diameter equal to that of the inside diameter of the coils to be wound; setting pins in the holes in the bottom plate; spaced turn winding all the pins of each row with a single electrically conductive Wire, making coils of the desired length in an electric series, using the pins in sequence as winding posts and leaving uncoiled wire ends in each row extending beyond the edge of the bottom plate; placing the U-shaped separator around the entire group of pins and over the extended wire, the wire being accommodated by the clearance slots; placing the top plate on the pins and separator to form a mold having an opening at the mouth of the U of the separator; casting a hardenable liquid plastic dielectric material through the mouth of the mold to surround and embed the coils; hardening the plastic dielectric material; and removing the top and bottom plates, the separator, and the pins from the embedded coils.

6. The method of claim 5 in which the plastic dielectric material is thermoplastic.

7. The method of claim 5 in which the plastic dielectric material is thermosetting.

References Cited in the file of this patent UNITED STATES PATENTS 1,608,530 Ripley Nov. 30, 1926 1,863,209 Shank June 14, 1932 2,371,107 Mapes Mar. 6, 1945 2,382,857 Camilli Aug. 14, 1945 2,767,742 Channell Oct. 23, 1956 2,829,426 Franklin Apr. 8, 1958 2,848,792 Reitz Aug. 26, 1958 2,883,447 Dahl Apr. 21, 1959 2,884,210 Strauss Apr. 28, 1959 2,901,736 Sylvester Aug. 25, 1959 2,948,953 Rayburn Aug. 16, 1960 

1. THE METHOD OF MAKING AN ARRAY OF HELICAL INDUCTIVE COILS EMBEDDED IN A HARENABLE PLASTIC DIELECTRIC MATERIAL FOR USE IN A MEMORY DEVICE, THE AXIAL HOLES OF SAID COILS BEING FREE OF THE DIELECTRIC MATERIAL INCLUDING THE STEPS OF PROVIDING A TOP AND A BOTTOM DIE PLATE HAVING AXIALLY ALINED HOLES TO RECEIVE PINS ON WHICH THE COILS ARE WOUND, SAID HOLES DEFINING THE CONFIGURATION OF THE COIL ARRAY, AND A U-SHAPED SEPARATOR PIECE HAVING THE THICKNESS OF THE DESIRED COIL LENGTH AND HAVING WIRE-CLEARANCE SLOTS; SETTING PINS IN THE HOLES IN THE BOTTOM PLATE; WINDING COILS ON SAID PINS, WITH INSULATED ELECTRICALLY CONDUCTIVE WIRE, IN AN ELECTRIC SERIES, LEAVING UNCOILED WIRE ENDS EXTENDING BEYOND THE EDGE OF THE BOTTOM PLATE; PLACING THE U-SHAPED SEPARATOR AROUND THE ENTIRE GROUP OF PINS AND OVER THE EXTENDED WIRE, THE WIRE BEING ACCOMMODATED BY THE CLEARANCE SLOT; PLACING THE TOP PLATE ON THE PINS AND SEPARATOR TO FORM A MOLD HAVING AN OPENING AT THE MOUTH OF THE U OF THE SEPARATOR; CASTING A HARDENABLE PLASTIC DIELECTRIC MATERIAL THROUGH THE MOUTH OF THE MOLD TO SURROUND AND EMBED THE COILS; HARDENING THE PLASTIC DIELECTRIC MATERIAL; AND REMOVING THE ARRAY OF EMBEDDED COILS FROM THE MOLD. 